The present invention concerns loose fill packing materials.
The most common packaging, wadding or fill used in cardboard containers is old newspapers. The most commercially marketed product is extruded or molded polystyrene blocks or shapes, which are typified by the recognized peanut design. The peanut shapes are some of the most widely known and accepted packing material and have been for many years.
There are decided disadvantages to the world's environment by the continued use of polystyrene shapes. The polystyrene shapes are reputed to have a half-life of more than 400 years, and possibly as long as 1,000 years. The shapes are lethal when eaten by wildlife. They float upon water, and being very light, they disperse with the speed of wind. The shapes generate static electricity, and special treatment is required when the polystyrene shapes are used to package electronic materials, which may be susceptible to damage by the packing material-generated static electricity.
A disadvantage of the polystyrene shapes is that they may be broken into small pieces, but the small pieces have the same half-life. Photo or UV reactive additives may be added to the polystyrene to make it break up into smaller pieces upon exposure of months or years to light. However, the pieces will not degrade, and have the same 400 to 1,000 year half-life as the major polystyrene shapes.
Packaging materials using polyurethane have been made by the inventor for more than a year. Such materials are made by separately dispensing two components (A and B) into a bag and hand kneading the bag to begin the reaction of the components, and then placing the bag in a box, followed by placing the article to be protected in the box, followed by another bag filled with the same packaging materials. The urethane foam made by the two starting materials expands to fill the box around the protected article with highly satisfactory shipping results. The inventor has identified that device as "PILLOW-PAK".
Some professional packers continue to use polystyrene peanuts or other shapes, such as extruded figure eight shapes, with the attendant environmental damage.
Unlike polystyrene, polyurethane has a short half-life, and eventually disintegrates into a suitable soil amendment.
The urethane foam produced by the inventor is based on a two-component system, which contains a polyisocyanate component, component A, and a polyol and catalyst component, component B. Both components are commercially available.
Component A is preferably a polymeric methylene diphenyl diisocyanate. Component B is primarily an activator for component A, which includes polyols, water and catalytic agents.
The two components react to produce polyurethane. Polyurethane is described as a class of synthetic resinous fibrous or elastomeric compounds belonging to the family of organic polymers made by the reaction of diisocyanates (organic compounds containing two functional groups of structure-NCO) with other difunctional compounds, such as glycols.
The best known polyurethanes are flexible foams, which are widely used as upholstery material, mattresses and the like. The polyurethanes of the present invention are rigid foams, such as those well known and used for insulation and for lightweight structural elements as cores for airplane wings and boat hulls.
Foamed polyurethanes result from the reaction of diisocyanates with organic compounds which are usually polyesters containing carboxyl groups. The reactions liberate bubbles of carbon dioxide and water vapor.
The fibers and foams generated by the reaction are usually white with dull luster, and are readily dyed. They absorb very little moisture. The great advantage to polyurethane is that it may be broken into small pieces which have a relatively short half-life, and which operate suitably as a soil amendment. If ingested by animals in reasonable quantities, it is believed to be substantially harmless.
While the polystyrene shapes have been marketed as loose packing materials for a long time and the bagged polyurethane foams have been coexistent for a shorter time, there has been no move as far as is known to make the polyurethane foam in small shaped, free-flow fill dunnage material, similar to the well known polystyrene shapes.
The prior art has included amylaceous materials in polyurethane foams in conjunction with stabilizing agents and anti-oxidants primarily for use as extenders. The prior art has used corn starch, corn flour and gelatinized corn flour, as well as acid-hydrolyzed gelatinized corn flour in conjunction with the stabilizing agents and anti-oxidants as extenders for the urethane foam. The starch has been mixed with the polyesters prior to foaming the foams. In other cases, the starch has been added to a completely reacted liquid reaction product of the polyester and diisocyanate, and has been added to liquid prepolymer formed by reacting organic polyisocyanate with a polyether or polyester. Carbohydrate fillers in polyurethane foams have been described as having relatively high functionality. Complex steps for including oxyalkylated starches and the use of starch-based polyols have been described in prior art. Phosphorous derivatives of starch polyethers have been used to give polyurethane foam flame-retardant capabilities.
Polyurethane foams containing stabilized amylaceous materials, which have been stabilized by treating with a stabilizing agent or by removing substantially all, or at least a major portion, of the oxidizable materials, have been described.
A recent patent describes the use of substantially pure starch with a high amylose content in an expanded form as a substitute for polystyrene peanuts.
None of the prior art has suggested use of such starch-extended foams as packing agents, and none have suggested simplified methods of including the starch in the foam.
A need for a better biodegradable free fill expanded foam packing material persists.